The present invention relates to recording and demodulation devices for an electronic still camera or the like in which a data signal is recorded on a magnetic medium in the DPSK mode and for reproduction is directly A/D converted so as to determine the phase of the signal.
On a magnetic medium used for an electronic still camera there are recorded in a single track in frequency-multiplexed form a luminance signal Y, color difference signals B-Y and R-Y and a data signal ID.
The data signal ID contains information as to whether the recorded image is a frame image or a field image, the track number of the recorded image, the date of recording, and the like. The recording format for the ID signal is shown in FIG. 10.
As shown in FIG. 10, 108 H (H indicating one horizontal period of an image signal) allocated to the user area may be recorded with one bit recorded in either 2 H or 4 H. For all remaining portions of the signal though, one bit is recorded in 4 H.
The data signal ID is DPSK modulated in accordance with its individual "0" and "1" bits. The color difference signals R-Y and B-Y are line sequenced every H to be frequency modulated. The luminance signal is also frequency modulated. Each of these signals is recorded using frequency multiplexing. However, the modulated data signal f.sub.ID and the modulated color difference signal f.sub.R-Y have adjacent frequencies, and they may instantaneously overlap.
Additionally, the data signal ID is extracted from the reproduced multiplexed signal obtained at the output of the magnetic head with the use of a filter having constants corresponding to the DPSK modulation frequency.
However, when the multiplexed signal is reproduced, there occurs a disruption in the continuity of the phase of the separated data signal f.sub.ID at times of data bit transitions from "0" to "1" or vice versa due to the operation of the filter. Further, since the frequency band of the modulated data signal f.sub.ID overlaps a portion of that of the modulated color difference signal f.sub.R-Y, when the modulated data signal f.sub.ID is directly demodulated by A/D conversion, there occurs a problem in that precise demodulation of the data signal ID is difficult.
As can be further seen from FIG. 10, the data signal ID is recorded with one bit per 4 H or 2 H starting with the 29th H as counted from the first H after the rise of the vertical synchronizing signal V-SYNC for even-numbered fields, and at the same point but delayed by 0.5 H from the above case for odd-numbered fields.
As a result, the point at which the phase of the modulated data signal f.sub.ID changes will always fall at the head of odd-numbered Hs, but not at the head of even-numbered Hs.